W: GPG error: http://repository.spotify.com stable InRelease: The following signatures
couldn't be verified because the public key is not available: NO_PUBKEY 082CCEDF94558F59
W: Failed to fetch http://ppa.launchpad.net/qbzr-
dev/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/qbzr-dev/ppa/ubuntu/dists/precise/main/binary-
i386/Packages 404 Not Found

I'm a bit new to ubuntu, but I wanted to figure out how I can go about fixing this issue.